1. Field of the Invention
This invention relates to a fiber crimping apparatus which is designed to give waves to the synthetic fibers formed straight by fiber drawing devices, and particularly which is provided with a ring roller of a comparatively large diameter and an inscribed roller which contacts the ring roller internally in such a manner that these two rollers rotate in the same direction at the same surface speed, while pressing against each other and which can give waves to the fiber bundles being fed in succession between these two rollers.
2. Description of the Prior Art
Fiber crimping apparatus in which a fiber crimping section is set comparatively long by forming a nip roller for crimping fiber bundles as an inner contact type such that high speed rotation of the nip roller, that is to say, speed-up of the crimping process can be achieved, are disclosed in U.K. Patent No. 1,408,235, U.S. Pat. No. 4,908,920 and Japanese published unexamined patent publication No. Hei.1 (1989)-201,540.
The nip rollers provided in the above-mentioned conventional apparatus are formed such that the surfaces of the outer and inner rollers contact the fiber bundles which are parallel to each other. The fiber bundles fed between these two surfaces are made flat and oblong to some extent by passing a guide at an earlier stage of crimping. But, when the fiber bundles pass the nip roller, both sides of the fiber bundle become thin and, accordingly, pressure on those parts is insufficient compared with that on the relatively thick central part.
Further, the rotating power of the rollers is insufficient compared with that at the central part and causes delays in feeding of the fibers. This results in an uneven crimping, that is to say, a production of irregular waves or a mixture of unwaved fibers or a flying out of fibers from among the delayed fibers on the both sides to outside of the pressing surfaces of the rollers. For that reason, it has become difficult to carry out homogeneous crimping of the fiber bundles without reducing the high-speed processing.